The present invention relates to a heat dissipation module and in particular to a heat dissipation module with reduced weight.
Precision electrical components often generate excess heat which cannot be dissipated by natural or forced convection. For accelerated dissipation of heat from the electrical components, a heat sink is typically disposed on heat sources, with the heat dissipated more thoroughly via fins thereof.
Heat sinks using fans still have limitations dissipating heat rapidly. For example, the temperature difference of the airflow between the surfaces of fins and the heat sink is only 5–10° C., whereby insufficient temperature gradient and heat resistance generated by the material and structure of the heat sink may reduce the heat dissipation efficiency of the fins below 70%. Thus, the typical heat sink is limited in heat dissipation efficiency.
FIGS. 1A and 1B show a conventional heat dissipation module 10. The heat dissipation module 10 comprises upper and lower cases 12 and 14 connected to each other. The cases 12 and 14 have porous structure 18 on the inner surfaces thereof, which is create by sintering and impregnated with liquid. The space between cases 12 and 14 is evacuated before sealing, creating a vapor chamber. When a heat source (such as a CPU) 16 generates heat and transmitted to the heat dissipation module 10, the liquid in the porous structure 18 of the lower case 14 is vaporized and rises to the upper case 12. Meanwhile, a fan (not shown) is disposed outside the upper case 12 such that vapor liquid in the porous structure 18 of the upper case 12 is condensed, and flows down to the porous structure 18 of lower case 14, completing an operation cycle for the heat dissipation module 10. Since the surface areas of the cases 12 and 14 exceed the surface area of the heat source, heat is dissipated.
However, to meet requirements for structural strength when contacting heat source 16, the wall of the lower case 14 must be thick enough to be processed (as shown in FIG. 1B). The contact area between the heat dissipation module 10 and the heat source 16 is part of the lower case 14. The lower case 14 can deform from its own weight after prolonged use, resulting in incomplete or interrupted contact with heat source 16, decreasing heat dissipation. As thickness of the heat dissipation module 10 is increased, weight increases accordingly, such that an electronic device utilizing the heat dissipation module 10 cannot meet small scale requirements.
Another heat dissipation module 20 is therefore disclosed as shown in FIG. 1C. The difference between heat dissipation modules 10 and 20 is that the lower case 24 is thinner to decrease the weight of the heat dissipation module 10. The outer surface of the lower case 14 is welded with a metal plate 22 to contact the heat source 16, providing sufficient structural strength. The surface area of the lower case 24 exceeds the surface area of the metal plate 22, and the surface area of the metal plate 22 exceeds the surface area of the heat source 16.
However, while this method decreases weight of the heat dissipation module 20, a welding layer 28 is required between the metal plate 22 and the lower case 24. The welding layer 28 increases heat resistance between the heat source 16 and the heat dissipation module 20, decreasing heat dissipation efficiency.